Fluid compressor and method of cooling the same



Dec. 28,1926; 1,611,866

B. S. AIKMAN FLUID COMPRESSOR AND METHOD OF COOLING THE SAME Filed Sept. 15. 1924 3 Sheets-Sheet 1 tl{1'fir'a, s e,s' 6 (6771007225 5117-7571 .5: diff/War;

Dec. 28, 1926. 1,611,866

B. s. AIKMAN- FhUID COMPRESSOR AND METHOD OF COOLING THE SAME Filed S m- 5. 1924 3 Sheets-Sheet 2 Dec. 28 1926. v 1,611,866

as. AIKMAN F'bUID COMPRESSOR AND METHOD OF COOLING THE SAME Filed Sept. 15. 1924 3 Sheets-Sheet 5.

Patented Dec. 28, 1926.

-fuN TEos T AT1-:s

ELECTRIC COMPANY, OF MILWAUKEE,

SIN.

1,611,866 PATENT, orrl 'ca.

sun/row s. AIRMAN, or MILWAUKEE, wrsconsm, asszenon 'ro NATIONAL 15min a wrsconsm, A conronarron or WISCON- FLUID OOLTPBESSOR AND. METHOD OF COOLING THE SAME.

Application flIed'Se'ptemberIE, 1924. Serial No. 787,725.

My invention relates to fluid compressors of the sleeve valve and cylinder type, such as disclosed in the French patent to Renault, and provides an improvement in structure f5 and method of coolmg.

Where a compressor is to be operated continuously in compressing a fluid to terminal pressures of three atmospheres or more, means must be provided for preventing excessive temperatures incidental to the compression of the fluid other than the mere radiation of the heat from the cylinder head and walls.

The heat which is enerated in com ressl5 ing the fluid is con ucted to the cy i'nder head, the piston head and to the walls, and it must be moved through the head and walls to the outside if the temperature is to be controlled. The heat that ma be trans- ,zo mitted by conduction to the wa is through continuous duty at final discharge pressures.

of three atmospheres or more, it is consider: ed the best practice at present to surround the compression chamber as nearly as possible by a jacket through which water is passed. This establishes generally a high promote the efficiency of .the compressor. 7 Q Water jacketing is not entirely satisfactory since it is not possible to completely surround the compression chamber by the water jacket, as the compressor piston of a single acting compressor forms one end 'of the chamber which cannot be practically water-cooled without danger to the lubrication and excessive complication in construction. The cylinder head with itsvalves'can be water-cooled onl partially, as the space which suction and ischarge pockets occupy in many compressors cannot be SQtlSffi-Ctfl.

air, I' refer rily cooled. Furthermore, they comprise the major portion of the active area of the com, pressor head. It is at the head and top of the cylinder wall that the highest temperatures will be reached during) sion, and since this area cannot e reached by water-cooling in a satisfactory degree,

it will be seen at once that these parts are subject to excessive temperatures even when other parts are fairly cool.

The cylinder walls may be satisfactorily cooled but they donot have a great influence upon the terminal pressures. The cooling of the side walls of the compression chamher is useful in maintaining a better lubrication of the piston and, ence, is highly useful. It does not, however, appreciably promote the volumetric eificiency nor the ability to operate continuously,.'so far as temperature rise is concerned, as it maintains only the mechanical lubrication.

Another ditficulty with-com ressors of the conventional type is that the clbarance at the discharge end of-the com ressing chamber 1n boph the compression c amber. and in the va ve compresockets, contains heated fluid at the end of 'the compression stroke-which, to-

gether with the slippage of the discharge valve, allows the heated air to expand back into the compression chamber 'as'the piston starts the suction stroke. This fluid being at the terminal tem erature, raises the general temperature 0 the fluid which is introducedinto the com ression chamber by the suction stroke and, ence, there is a constant building up of temperature due to inability to scavenge the cylinder at the end of the discharge stroke. difference of temperature between the inside 40 and outside walls and tendsto According to my invention, I scavenge the clearance space immediately upon the completion of the-compression stroke, displacing the heatedlair or other fluid with free disclosed in the present drawings and specification'm an air compressor, it is to bean-1;

invention as, loo

derstood. that the invention may be employed g incompressing other compressible fluid, and i herein where I speak of an air compressor or generally to a fluid ice j no I example, by intermittent stages of operationor multi-stage compression or the like.

According to the present lIlV\ll'.l0Il,'I provide a method of cooling whiclrwill be applicable for cooling a compressor by the use of a current of free fluid which is being compressed that will permit of high rotative speeds under continuous operation without exceeding permissible temperatures.

My compressor and cooling system provides a structure which is self-contained,-

that is, the cooling system is made a part of the compressing unit, and it does not depend u on an external source of cooling fluid.

- atures are not detrimental.

' accompanyin urthermore, since I use the same fluid which is being compressed, freezing temper- The unit is light in weight and simple, and inexpensive to manufacture.

In order to acquaint those skilled in the art with the manner of constructing and operating a device embodying my invention, I shall now disclose in connection with the drawings a specific air compressor embo ying my invention.

In the drawings Fig. 1 is a vertical central cross section;

Fig. 2 is a side view showing a part of the compressor in'section;

Fig. 3 1s a vertical section similar to that 40 1 shown in Fig. '1 of the upper end of the cylv downward stroke;

inder and the head showing the piston on its Figs. 4 and 5 are cross sections taken on the lines 4-4 and 5 :5, respectively, on

i 3. i Tn the embodiment shown. in the drawlngs, the com ressor 1 and its driving motor 2 are mounte upon a common base 3 with a flexible coupling 4 connected between the motor shaft 5 and the fly wheel 6. The fiy' wheel 6 is provided with bosses or lugs 7 to winch are clamped the flexible discs 8, these dlscs bemgin turn connected to the motor shaft through spider arms 9. The fly wheel 6 1s keyed or otherwise secured' to the end-ofv the crank shaft 10, this crank shaft having bearings 11 and 12 supported in the side ,walls of the crank case 13. The crank case 13 is preferably provided with drip cups 14 communicating with the bottom of the crank case 13 and surrounding the lower part of the crank shaft 10. -The crank case 13 is preferably made in two sections, that is, 'split npon theline of the crank shaft bear-- upon the-base 3, this extension 15 being suitable in height to bring the crank shaft of the compressor in line with the motor shaft and also providing sufiicient clearance for the fly wheel 6. The upper. section of the crank case 13 merges into a cylinder housing 16 having a" cylindrical bearing ring 17 at its lower end and providing also a similar bearing ring 18 at an intermediate point adacent the upper end. The cylinder housmg 16 which may be termed the cylinder contains a suitable sleeve or liner 19 having cylindrical bearing surfaces cooperating 'with said bearing surfacesv 17 and 18, as ndlcated at 20 and 21; As the piston has its bearing inside of the liner 19 and the actual work ofcompressing the fluid is carried on 7 inside of this liner, I may term the liner herein the working cylinder, since functionally that is its duty. This is to distinguish it from that part of the'structure, namely, the cylinder 16, the function of which is to support the liner or working cylinder and the cylinder head. This liner or working cylinder in addition to its function of operating in conjunction with the piston as the working cylinder also functionally serves as a sleeve valve operated by ring friction. The remaining outside surfaces of the sleeve or liner 19 may be corrugated, as indicated at 22 and 23, for greater efliciency in coolin The cylinder housing 16 has a cylinder head 24 secured as by means of the cap screws 25 to the top thereof. This head contains a suitable seating rin 26 in position to engage with the-finturned ange 28 of the upper end of the sleeve or liner 19 to make a fluid tight joint. The ring 26 surrounds the discharge opening 27 which has a valve seat 29 adapted to be closed by'the discharge Y discharge connection 33 which is provided with a threaded seat or socket 34 to receive the discharge pipe. The check valve is held to its seat by a coiled spring 35 seated in the hollow stud 32. A discharge chamber 36 is formed about the valve and its guide by a shell .or cylindrical housing 37.

This shell or cylindrical housing is formedintegral with the cylinder head at its lower end, and at its upper end is threaded to receive the fitting 33'. s The shell or housing 37 is joined to the cylinder headby a relatively narrow neck. This is of importance because it limits the contact of the hot compressed air with the top of the cylinder head. It will be noted that the use of this narrow neck permits the top of the cylinder head above the yielding seat 26 to be cooled constantly and it limits the conduction of heat from the compressed air in thepocket 36 to the said yielding seat 26. Since this seat is made of yielding material, it is important that it be kept relatively cool or it will quickly deteriorate.

While the above is the Construction preferred for embodying the invention in a simple single stage; compressor, it is to be understood that the dischar e valve construction may be widely varied Within the limits of my invention. 1 r

The discharge chamber 39 is surrounded by a conduit orwind chest 38 which has openings, as indicate-d at 39, for discharging air against the top of the cylinder head 24 preferably at a. point closely adjacent the discharge valve seat. This wind chest 38 f is connected by a conduit or tunnel 40 which is formed integral therewith and which is fastened as by means of the flanges cylinder is opened.

space 41 to the side wall of the cylinder housing, a boss 42 being formed at that point. Diametrically opposite the boss 42 there IS formed a similar boss for air admission. To the boss 43 I have connected the flanged end .of the blower discharge pipe 44, this pipe being formed integral with the housing 45 of a suitable blower or fan 46. A wind box or conduit is formed about the upper end of the liner or sleeve 19, as indicated at 47, in order to permit the air delivered by the fan or blower 46 to surround completely the upper end of'th sleeve or liner 1.9.

Preferably, but not necessarily, restricting bafiles 48 arearranged in the discharge ends of the passageways or chambers 47. This. is for t e purpose of re:tricting the flow of air while the sleeve or liner 19 is in raised position and the working cylinder 19 may be provided without departing from the spirit of my invention. The cylinder lin'er 19 at the enlargement 21 has a projecting ring or annular shoulder 53, which is adapted to contact witha yielding ring 54 for stopping the downward motion of the liner 19 to silence the operation of the device.

The compressor piston 55 has suitable rings, as is well understood by those skilled in the art, for maintaining a fluid tight fit between the piston and the walls of the compression chamber, in this case the liner 19. The iston 55 is connected toa suitable connectm ,rod 56 of any preferred or usual constructionto the crank pin 57 on the crank shaft 10.

51 between the cylinder housing 16' In the device illustrated, the fan or blow er 46; is driven by means of a grooved pul-, ley .58 on the blower shaft, the outer end of the shaft being supported upon a bracket 59 mountedon the side walls of the cylinder housing 16. Z A round belt 60 is'trainedover the pulley 58 and the fly wheel 6, a suitable groove 61 being formed on the peripherymf the fly wheel 6 next to the compressor.

The particular blower 46 which I have illustrated is illustrative of any suitable device for creating ,a current of air in excess of the amount required by the downward motion of the piston 55 when the compressor is operating at its rated speed. That is to say, any suitable device for supplying a flow of free air, preferably at a slight pressure above atmosphere, may be provided instead of the particular fan shown at 46. The fly wheel 6 may be formed with varies for creating a. blast of air which will serve the purpose.

The operation follows 2- i The cylinder liner 19' which forms the side walls and a part of the end walls of of the device is as the compression'chamber, is adapted to be moved up and down with the piston 55 by the ring friction; that is, the friction between the piston and the liner created by the piston rings. The liner 19 is per.- mitted to move only a very short distance until the flange or-ring 53 strikes the'yielding stop or seat 54 in'the downward direction.

This is shown in Fig. v3. The blower 46 which has been delivering air through the pipe 44' and the passageways or box 47 about the top of the liner, now blows air through the opening between the top of the liner and the bottom of the cylinder head, thereby sweeping out the heated air which remains in the clearance space and, at the same time, cooling on by contact the top of the piston 55 and the bottom surface of the head 24, the valve 30, and the yielding seat 26. The yielding seat26 is permissible because the temperature is kept relatively low lit) and it has the. advantage of quieting the 6 operation of the-device very materially and securing a better fit'than could be secured by a plainflat metal-to-metal contact. The air which is blown in b the blower 46 is considerably in excess 0 the maximum intake requirements offthe retreating piston 55. In. the "form illustrated, I have .pro vided forv an excess flow of air at least'25 per cent greater than the air inflow to the compression chamberduring the maximum speed of compressor p ston movement 1n its downward stroke. Thus, at the early mains in the clearance space scavenged,

but the continuing blast of air sweeps over the heated surfaces cooling the same. The

air after it cools the top of the liner, the

bottom of the cylinder head and the top of the piston,-is driven on through the conduit 40 into the wind box 38 and there through the nozzle 39 is discharged against the cylinder head and the receiving chamber about the discharge check valve 31. Upon the piston reaching the bottom of the stroke. the motion thereof is reversed andat this time the ring friction seizes 'the liner '19 and the liner and the piston move up until the flange 28 on the liner strikes the yielding seat 26, closing the compression chamber, and the remainder of the stroke of the piston 55 compresses the fluid and drives it out through the delivery port 27 past the check valve 30. During this time, the top of the liner and the adjacent parts of the cylinder head are being tooled,

and the blast from the nozzle 38 is effective in cooling the receiving or delivery chamber 36. The vibrating motion of the liner 19 need be only very light to secure a relacylinder.

The purpose of the inturned flangeat the tively large opening into the interior of the top of the liner, indicated at 28, is to insure seating with internal pressure. This flange need be onlv great enough to insure that the cylinder will be maintained closed duringthe'compression stroke, and should not be so great that ring friction will not readily open the cylinder when the piston begins to move downwardly.

While I have described an air compressor operating in atmospheric air at usual temperatures', it is to be understood that the compressor may be used to compresslgas with-out departing from the spirit of the invention vby enclosing the same in such a manner as to employ the medium which is compressed as'a'cooling medium. v 1

It will be understood also, that instead of using a blower to forcethe air through as above described, an exhauster may be used at the opposite end to permit atmospheric pressure to drive the air through the. passageway. The exhauster, however, has the the compression stroke.

disadvantage of lowering the etficieney of the compressor by reducing the pressure of the air in thecylinder at the beginning of The cooling air may be condu ted through a suitable conduit from anyv desired point and may be filtered if desired.

I do not intend to be limited to the detail shown or described. r Y

1. The method of cooling the piston and ,working' cylinder of an air compressor which comprises opening the c hnder at the beginning of the suction stro e and low stroke.

'ing free air into the workingcylinder in excess of the volume demanded by the dis:

placement of the piston.

2. The method of cooling a fluid compressor having a workin cylinder, a cylinder head and piston, whic comprises separating the working cylinder from the head at the beginning of the suction stroke of the piston and-blowing free fluid across the bottom of the cylinder head and across the piston head. I

3. The method of cooling a fluid compressor which comprises creating a current of free fluid into and out of the working cylinthe working cylinder than' it will hold during the'suction stroke. 7. The method of cooling an air compressor which comprises blowing a'ir completely across the bottom of the cylinder head dur ing each suction stroke.

8. The method of cooling-a compressor which comprises blowing a blast of air across the bottom of the cylinder head and out of the working cylinder during the suction 9. The method of operating an air oompressor which comprises forclng a current of air into the working cylinder and out of the same during the suction stroke.

10. In a compressor, a cylinder having a movable liner, a head adapted to be engaged by the liner upon the beginning of 7 the compression stroke, a yielding stop carried by the cylinder, and means on the liner for engaging said stop upon movement of the liner away from the cylinder head.

11. In combination a cylinder having a.

movable liner, a head havin a ieldingseat adapted to be engaged by said l1ner,'a yielding stop, means on the liner for engag1ng said stop upon movement of the liner away from the head. I

12.,In combinatioma cylinder havlng a :cylinder head, a movable liner, a piston having rings engaging the liner, said liner being adapted to he moved by ring friction,

and means for forcing a current of air through the opening between the Inner and I the head during the suction stroke of the engine. i g y 13. In'combination, a cylinder havmg a head,-a-liner, a 631pistmi for the liner, said liner being move by friction with the pis-.

ton, and means for blowing a continuous blast of air upon the upper end of the liner where it engages the head. 4

14. In combination, a cylinder housing, a movable liner in the housing, said housing having a head, the liner being adapted to. engage said head, a piston in the liner for moving the liner away from the head upon the beginning of the suction stroke and against the head at the beginning of the compression stroke, said housing forming a wind box about the upper end of the liner and a blower operated concurrently with a the compressor connected tosaid wind box.

15. In combination, a cylinder. housing containing a movable liner, said housing having a cylinder head adapted to be en'-- gaged by the liner upon the beginning of moved away from the head at the beginning of the suction stroke, said housing comprising a wind box surrounding the top' of the from the head.

liner, and baffle means about the sides of the line-r in said wind box. I

16. In combination, a cylinder having a c linder head and a liner adapted to contact tierewith to form a closed working chain her, said liner being movable by ring friction away fromsaid head and against said head, and means for creating a forced current of air completely across the'bottom of the head when the liner is moved away 17. In combination, a cylinder housing havin a movable liner, ahead having a seat or the end of the liner, a, wind box about the end of the liner and under said head, means for flowing air into said wind box, a discharge valve for the head, and means for discharging air from the wind box upon the top of the head for cooling said head adjacent the discharge valve.

18. In an air compressor, a sleeve valve.

. and means for creating a current of air in contact with the sleeve valv operated concurrently withthe compres'or for cooling said sleeve valve.

19. In combination, a cylinder housing having a movable liner therein adapted to be moved by ring friction, a head, ada ted to be engaged by the liner, a wind box :1 out the upper end of theliner,-an intake for the wind box o rone side of the housing, a bloweer having its discharge, conn'ectedto said intake, a: discharge connection for the wind 7 box opposite to the intake, and means communicatingwith said discharge for directing the airtherefromhpon the top of the cylinder head.

20. In combination, a cylinder having a movable sleeve said sleeve having an inturned fiange, a head,'a spring actuated discharge check valve on said head, a pistonin the sleeve, and yieldable stationary stop see in each direction, the yiel dable stop means including a yieldable valve seat on the cylinder head adapted to be engaged by said inturned flange.

21. In combination, a cylinder having a head, a movable liner, a discharge valvepocket connected to the head by a relatively the frame, .a central discharge port, a check.

valve therefor, a ieldi'ng annular seat surrounding the disc large port and co-operating with the to of the movable cylinder sleeve,v and a piston having rings fitting in the cylinder and adpated to move the plunger by ring friction.

' 23. In a compressor, a cylinder frame, a

cylinder head mounted thereon, a movable sleeve cylinder in the frame, a discharge checkvalve chamber connected to the top of the head by-a neck of relatively small diameter, a discharge port extending through the head and communicating wit-h the chamber, a check valve for said port,

a ring of yielding material surrounding the discharge port and forming a valve seat on the bottom of the cylinder head for the upper end of the sleeve cylinder, and a piston having piston rings fitting in the cylinder and adapted to move thecylinder to and from its'seat at the beginning of the respective compression and suction strokes.

N 24. In a compressor, a c linder frame, a head for the frame, the cylinder frame having radial orts at its upper end adjacent the head, he head having a substantially flat bottom surface and having a yielding annular seat mounted. therein, said head having a discharge port through the central part thereof, a discharge check valve therefor, a sleeve forming acylinder mounted for limited axial motion in the cylinder frame, the upper end of the cylinder cooperating with the annular seat to form avalve, and a piston having rings engaging the inner surface of the sleeve to shift it by ring friction at the beginningifi each stroke of the piston.

25. In a compressor, a cylinder head having a centraledischarge valve pocket disposed above'and joined to the head by a relatively small '.-neck to limit thenrea of contact of thhot compressed air and conduct-ion of heat therefrom to the cylinder head, there being a central discharge passage leading through the head and neck head by ring friction, and means for mov into the valve pocket, and a check valve disposed in said pocket and controlling said discharge passage.

26. In a compressor, a cylinder frame having a head, a liner guided at its upper and lower ends in the frame and adapted to be moved into and out of .contact with the ing cooling air in contact with the exterior of the liner' between the parts where it is guided in the frame.

27.'In a compressor, a hollow cylinder frame having bearings,-a liner in the frame. mounted in said bearings, a head on said frame adapted to be engaged by said liner, 16

along the intermediate part" of the; liner for 2o cooling said part of the liner.

In witness whereof, I hereunto subscribe my name this 11th day of September, 1924.

BURTON S. AIKMAN. 

